/*
 * Copyright (C) 2017 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import com.google.common.collect.TreeTraverser;
import com.google.common.graph.Traverser;
import com.google.errorprone.refaster.annotation.AfterTemplate;
import com.google.errorprone.refaster.annotation.BeforeTemplate;
import com.google.errorprone.refaster.annotation.Placeholder;

/**
 * Refaster rules to rewrite usages of {@code com.google.common.collect.TreeTraverser} in terms of
 * {@code com.google.common.graph.Traverser}.
 */
@SuppressWarnings("DefaultPackage")
public class TraverserRewrite
{
    abstract class TreeTraverserPreOrder<N>
    {
        @Placeholder
        abstract Iterable<N> getChildren(N node);

        @BeforeTemplate
        Iterable<N> before1(N root)
        {
            return TreeTraverser.using((N node) -> getChildren(node)).preOrderTraversal(root);
        }

        @BeforeTemplate
        Iterable<N> before2(N root)
        {
            return new TreeTraverser<N>()
            {
                @Override
                public Iterable<N> children(N node)
                {
                    return getChildren(node);
                }
            }.preOrderTraversal(root);
        }

        @AfterTemplate
        Iterable<N> after(N root)
        {
            return Traverser.forTree((N node) -> getChildren(node)).depthFirstPreOrder(root);
        }
    }

    abstract class TreeTraverserPostOrder<N>
    {
        @Placeholder
        abstract Iterable<N> getChildren(N node);

        @BeforeTemplate
        Iterable<N> before1(N root)
        {
            return TreeTraverser.using((N node) -> getChildren(node)).postOrderTraversal(root);
        }

        @BeforeTemplate
        Iterable<N> before2(N root)
        {
            return new TreeTraverser<N>()
            {
                @Override
                public Iterable<N> children(N node)
                {
                    return getChildren(node);
                }
            }.postOrderTraversal(root);
        }

        @AfterTemplate
        Iterable<N> after(N root)
        {
            return Traverser.forTree((N node) -> getChildren(node)).depthFirstPostOrder(root);
        }
    }

    abstract class TreeTraverserBreadthFirst<N>
    {
        @Placeholder
        abstract Iterable<N> getChildren(N node);

        @BeforeTemplate
        Iterable<N> before1(N root)
        {
            return TreeTraverser.using((N node) -> getChildren(node)).breadthFirstTraversal(root);
        }

        @BeforeTemplate
        Iterable<N> before2(N root)
        {
            return new TreeTraverser<N>()
            {
                @Override
                public Iterable<N> children(N node)
                {
                    return getChildren(node);
                }
            }.breadthFirstTraversal(root);
        }

        @AfterTemplate
        Iterable<N> after(N root)
        {
            return Traverser.forTree((N node) -> getChildren(node)).breadthFirst(root);
        }
    }
}
